Urea pump assembly for an exhaust gas treatment system

ABSTRACT

Exemplary embodiments of the present invention are directed towards improved systems and methods for the delivery of urea to an exhaust gas treatment system. In one exemplary embodiment, a urea pump assembly for an exhaust treatment system is provided. The pump assembly includes a housing comprising: a housing chamber, a first fluid inlet and a first fluid outlet, the first fluid inlet being in fluid communication with the first fluid outlet through a first conduit. The housing also comprises a second fluid inlet and a second fluid outlet, the second fluid inlet being in fluid communication with the second fluid outlet through a second flexible conduit. The second flexible conduit is located within a portion of the housing chamber and in thermal communication with the first conduit. The pump assembly also includes a pump located within the housing chamber, the pump being engaged with the second conduit and configured to move fluid between the second fluid inlet and the second fluid outlet.

FIELD OF THE INVENTION

Exemplary embodiments of the present invention are directed towards improved systems and methods for the delivery of a urea solution to an exhaust gas treatment system.

BACKGROUND

Exhaust emission control has been and will continue to be of interest as effects of emissions from stationary and transient emission generating devices are continually being understood. This, along with government mandates, have caused manufacturers of emission generating devices, particularly internal combustion engines, to develop methods and devices for controlling the content of emissions emanating from such devices. In one particular sector, due to the advantage of diesel burning engines over gasoline burning engines, advancements of emission control for diesel engines are continuingly being sought. These advancements include emission control devices configured for removing particulate matter from an exhaust gas stream and/or converting certain exhaust gases, such as NO_(X) to other specific exhaust gas outputs such as NO₂ and CO₂.

One particular advancement in the reduction of emissions from diesel and gasoline burning engines is the application of an ammonia solution to the exhaust gas stream prior to treatment by one or more components of an exhaust gas treatment system. In one particular configuration, a urea solution is added to the exhaust gas stream. The addition of ammonia and/or urea solution improves efficiency of the conversion of NO_(X). However, during certain operation conditions, such as extreme cold temperatures, the ammonia or urea solution may become frozen, thereby causing a loss in the ability to inject the solution into the exhaust gas stream. Further, increased effectiveness of the ammonia or urea may be achieved at higher temperatures.

While certain injection systems have been provided for the introduction of urea, few systems contemplate the addition of heat for prevention of freezing of the ammonia or urea. This is in part due to the relatively new application of urea to improve efficiency of exhaust gas treatment components. When heating systems are employed, such systems are located with an ammonia or urea supply tank or along a supply line. However, these configurations require the addition of components to the exhaust treatment system, thereby adding further component and/or assembly cost. Further, these heating systems often continually draw unnecessary energy (e.g. electricity) away from the engine system thus reducing battery life and/or power to the engine.

In view of the foregoing, there is a need for improved urea delivery systems capable of heating ammonia, urea or other fluids used for injection into an exhaust gas stream.

SUMMARY OF THE INVENTION

Exemplary embodiments of the present invention provide improved systems and methods for the delivery of ammonia, urea or other solution to an exhaust gas stream for use with an exhaust gas treatment system.

In one exemplary embodiment, a urea pump assembly for an exhaust treatment system is provided. The pump assembly includes a housing comprising: a housing chamber, a first fluid inlet and a first fluid outlet, the first fluid inlet being in fluid communication with the first fluid outlet through a first conduit. The housing also comprises a second fluid inlet and a second fluid outlet, the second fluid inlet being in fluid communication with the second fluid outlet through a second flexible conduit. The second flexible conduit is located within a portion of the housing chamber and is in thermal communication with the first conduit. The pump assembly also includes a pump located within the housing chamber, the pump being engaged with the second conduit and configured to move fluid between the second fluid inlet and the second fluid outlet.

In another exemplary embodiment, an exhaust treatment system is provided. The exhaust treatment system includes an exhaust gas conduit extending between an internal combustion engine and an exhaust gas treatment device. The exhaust gas conduit is configured to guide an exhaust gas stream from the internal combustion engine to the exhaust gas treatment device for treatment of the exhaust gas stream. The system also includes a urea pump assembly for providing urea to the exhaust gas stream. The urea pump assembly includes a housing having a first conduit configured for receiving and guiding a first fluid from the internal combustion engine through a first internal portion of the housing and a second conduit in thermal communication with the first conduit and the first fluid, the second conduit receives and guides urea solution through a second internal portion of the housing. The pump assembly also includes a pump located in the second internal portion for causing movement of the urea solution along the second conduit. The pump assembly further includes a fluid outlet in fluid communication with the second conduit and the exhaust gas conduit or exhaust gas treatment device, wherein the pump causes dispensing of the urea solution into the exhaust gas stream through the fluid outlet.

In yet another exemplary embodiment, a method of heating a urea solution for delivery to an exhaust treatment system is provided. The method includes: fluidly coupling a urea pump assembly to a first fluid system of an engine to provide a first fluid flow through the urea pump assembly; fluidly coupling the urea pump assembly to a urea solution supply to provide a urea solution to the urea pump assembly; and activating a motor to cause movement of the urea solution through the urea pump assembly and to cause discharge of the urea solution into an exhaust gas stream, wherein during movement of the urea solution through the urea pump assembly the urea solution is heated by the first fluid.

The above-described and other features and advantages will be appreciated and understood by those skilled in the art from the following detailed description, drawings, and appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects, features, advantages and details appear, by way of example only, in the following detailed description of embodiments, the detailed description referring to the drawings in which:

FIG. 1 illustrates a schematic view of the an exhaust gas treatment system of an internal combustion engine including a urea delivery device according to an exemplary embodiment of the present invention;

FIG. 2 illustrates a perspective view of a urea pump assembly according to an exemplary embodiment of the present invention;

FIG. 3 illustrates another perspective view of the urea pump assembly shown in FIG. 2;

FIG. 4 illustrates still another perspective view of the urea pump assembly shown in FIG. 2; and

FIG. 5 illustrates a cross-sectional view of a urea pump assembly according to an exemplary embodiment of the present invention.

DESCRIPTION OF THE EMBODIMENTS

Exemplary embodiments of the present invention provide improved devices, systems and methods for the delivery of urea solution or other ammonia containing solution to an exhaust stream of an internal combustion engine. Exemplary embodiments of the present invention further provide devices, systems and methods for the heating or thawing of urea solution or other ammonia containing solution prior to delivery to an exhaust stream of an internal combustion engine. It should be noted that an ammonia solution, urea solution and other similar types of agent, derivative or additive used for improving efficiency of exhaust treatment systems are hereforth generally referred to as urea solution. However, this should not be considered limiting as other solutions are contemplated, as described herein.

Exemplary embodiments of the present invention provide improvements to the delivery of urea solution to exhaust gas treatment systems. This improvement is achieved, at least in part, through a urea pump assembly fluidly connected to a vehicle fluid system, such as an engine coolant system, for receiving and utilizing heat from an engine to cause heating of the urea solution prior to injection into an exhaust gas stream. The use of a fluid heated in conjunction with operation of the engine, such as engine coolant, reduces the overall need for energy, e.g., electricity, for heating of the urea solution. Further, the improvements optionally include multiple heating sources for additional heating of the urea solution, an improved pump and other unique features and advantages as shown and described herein.

Through exemplary embodiments of the present invention, the effects of freezing to the urea pump assembly are substantially eliminated through the heating configuration of the pump and/or purging of urea solution from the urea pump assembly. Also, clogging from urea crystals, corrosion, erosion or freezing damage to valves or other components of the pump assembly are also reduced due to the reduction of pumping pressures, urea solution purging and/or elimination of typical pump valves and other components. Still further, manufacturing costs are realized through a reduction in components and reduction in complexity of the urea dispensing pump assembly or urea dispensing system.

Further, exemplary embodiments provide improved, e.g., reduced heating and/or thawing time of urea solution, improved cold starts particularly in cold climate, thereby minimizing urea consumption through precise metering device, close loop control and high precision urea dosing. Still other advantages include rapid heating of the urea solution through the use of heat energy from an associated internal combustion engine's coolant in conjunction with electrical heaters, low fluid shear rate and fluid pressure pulsation, positive displacement of the urea solution (due to the flow being proportional with a rotational speed of the pump, which allows precise flow control by speed adjustment), reduction or elimination of valves, which eliminates common valve issues such as clogging, deposit formation, corrosion or wear. Exemplary embodiments of the pump also provides high viscosity and solid contents capabilities, self-priming, reduction or elimination of vapor or air lock, flexibility in operation and mounting, low noise level, durability with respect to fluid abrasiveness, corrosive and solids, flexible tubing provide increase volume of frozen urea solution, seal-less pump eliminates urea leakage outside of the system and lowers the cost (due to elimination of seals).

In general, referring to the drawings, exemplary embodiments of the present invention are provided. The exemplary embodiments provide a pump assembly 10 for delivery of a fluid, such as urea, to an exhaust treatment system 12 having an exhaust treatment device 13. The pump assembly includes a housing 14 defining a first cavity 16 configured for receiving a first fluid, such as an engine coolant, and a second cavity 18 configured for receiving a second fluid, such as a urea solution. The first cavity includes a first conduit 20 extending between a first inlet opening 22 and a first outlet opening 24. The second cavity includes a second conduit 26 extending between a second inlet opening 28 and a second outlet opening 30. The pump assembly further includes a pump 32 having rotating and rotatably mounted actuator members 34 configured for engaging the second conduit to cause movement of the second fluid through the second conduit and hence second cavity. In the embodiment shown, pump 32 actuator members 34 are exposed, but opening 35 may optionally be closed by attachment of a suitable cover (not shown).

In operation of the above exemplary embodiment, the pump assembly receives the first fluid, such as coolant from an engine coolant system 36 of an engine 38, for causing heating of the pump assembly and a urea solution flowing through pump assembly 10. As the housing is heated through flow of heated first fluid through the first conduit, the heated housing thermally communicates with both first and second conduits and in turn causes heating of the urea solution flowing through the second conduit, which originates from a urea supply 40. This heating may be supplemented through one or more heaters 42 located at the second inlet opening 28, second outlet opening 30 or both. Alternatively, the heaters may be positioned on and in thermal communication with housing, first conduit or second conduit. Movement of the urea solution through the second conduit is achieved through one or more rotating actuators member 34 of the pump 32, which are also rotatably mounted. The one or more rotating actuator members are configured to depress a portion of the second conduit along a portion of its length (L) as it travels about an axis ‘A’ of the pump. This rotating and depressing or squeezing action causes fluid to flow in a direction from the second inlet opening to the second outlet opening, through conduit 43, and subsequently to an outlet 44, via dosing module 45 or otherwise, which is in fluid communication with an exhaust stream flowing through an exhaust system 46 of engine 38. The outlet may include a valve for controlling fluid flow, such as a poppet valve or otherwise.

In more detail, with specific reference to FIGS. 2-5, housing 12 is configured for receiving a first fluid for causing heating to the housing, first conduit and second conduit, and particularly fluids flowing through the second conduit. The housing is also configured for receiving a second fluid for heating, and further for causing movement of the second fluid to an outlet for heating, for dispensing of the second fluid into an exhaust gas stream. The housing is further configured for supporting components of the pump assembly as described herein or otherwise.

In one exemplary embodiment, the first fluid is an engine coolant and the housing is in fluid communication with an engine coolant system for receiving coolant from an internal combustion engine. In this configuration, the housing includes first cavity 16 having first conduit 20 extending between first inlet opening 22 and first outlet opening 24. The first cavity extends internally but also about an exterior portion of the housing to allow for other fluids and pump assembly components to be located within the first cavity and optionally heated by the first fluid.

The housing further defines a first inlet connector 48 and a first outlet connector 50 for fluidly connecting the first conduit to coolant system 36. The first inlet and outlet connectors may comprise any suitable connector for fluidly coupling components together. Optionally, the inlet and/or outlet connector may include or be in communication with one or more valves 52 for controlling fluid flow through the first conduit and housing. For example, in one exemplary embodiment the inlet and/or outlet include or are in fluid communication with a poppet valve or the like. Optionally, the one or more valves may be configured for providing fluid flow to the housing or bypassing the housing (not shown) to effectively fluidly disconnect the housing from the coolant system while still maintaining fluid flow through the coolant system.

In one exemplary embodiment, the housing is in further fluid communication with a urea supply and an exhaust system of an internal combustion engine. In this embodiment, the housing includes second cavity 18 having second conduit 26 extending between second inlet opening 28 and second outlet opening 30. The second conduit comprises a resilient flexible conduit configured to be depressed along a length (L) thereof. In one particular configuration, the flexible conduit is elastically depressible upon application of suitable force and configured to return to an original position after release of said suitable force. In operation, the urea solution enters the housing and the second cavity. Through the pump, a portion of the flexible conduit is depressed. As the pump moves (e.g., actuators 34 rotate) the portion of the flexible conduit being depressed moves towards the second outlet effectively squeezing the fluid towards the second outlet and the exhaust system.

In one exemplary embodiment, the flexible conduit is separately formed from the housing and placed therein. In this configuration, the flexible conduit extends from the second fluid inlet to the second fluid outlet. The flexible conduit is also arcuate in shape, and more specifically formed in a circular arc about an axis of the pump and more particularly around the rotatable actuating members of the pump. This orientation of the flexible conduit about the axis of the pump allows the actuating members of the pump, which also rotate about the axis of the pump, to continuously engage the flexible conduit during rotation to cause the above mentioned squeezing effect. The flexible conduit may be formed of any suitable resilient material configured for repeated application of force. For example, the flexible conduit may be formed of a plastic, rubber, silicone or other flexible resilient material.

Optionally, the housing may include additional suitable connectors for coupling a conduit in fluid communication with urea supply tank 38 to the pump assembly and for coupling the pump assembly to a fluid discharge outlet, such as one or more outlets 44 of a dosing module 45. In one exemplary embodiment, the suitable connectors are located proximate to the second inlet and second outlet, respectively. Such suitable connectors may include any suitable mechanical fastener such as threaded fasteners, other hose or tube connectors or otherwise. Also, it is contemplated that one or more valves may be located along the fluid flow path between the pump assembly and the urea supply tank and/or between the urea pump assembly and exhaust system for controlling fluid flow. The valves 52 may be electronically controlled valves in signal communication with the controller such that they may be selectively opened or closed by operation of the controller.

In one exemplary embodiment, the one or more outlets 44 comprise a portion of a dosing module 45 configured to provide dispensing of the urea solution from the pump assembly to the exhaust gas stream. In one configuration, the dosing module consists of a two piece member forming a flanged housing assembly, which includes a plurality of dosing poppet valves with an individual electric heater, arranged in a circular pattern about the exhaust gas flow and disposed at an angle, with respect to an exhaust gas flow axis. The dosing module housing includes an annular cavity that collects urea solution from a heated conduit of the pump assembly and feeds the individual poppet valve. The pressurized urea solution, or vaporized urea solution, transmits a force on the back of the poppet valve that exceeds a spring force of the valve for opening the valve for a time period for spraying a metered quantity of urea, as determined by the control module using data collected from the sensors. Each poppet valve has an individual electric heater to maintain the urea solution in liquid state or vaporize and deliver the urea solution into the exhaust stream for cold starting. In one configuration, the pumping system is located proximate to the exhaust system of an engine so as to minimize the length of the piping between the pump outlet and the dosing module

Also, the housing may further include one or more additional fluid connectors for causing or effecting fluid flow through the housing. This is particularly advantageous for removing fluid from within the first or second cavities or conduits. For example, in one exemplary embodiment the housing includes an additional inlet port 54 in fluid communication with the second conduit for flushing out fluid from within the second conduit. This is particularly advantageous during periods of extreme cold where fluids used for treatment of exhaust gas are prone to freezing. It should be appreciated that the housing may also include an inlet port for removal of fluid from within the first conduit in order to remove the first fluid thereform. In ether configuration, flushing of the first and/or second conduit may be achieved through an application of air, or another other inert gas or by evacuating the conduits, or otherwise.

It should be appreciated, as described therein, that the housing may be formed or otherwise include additional components for use with the pump system, exhaust treatment system or otherwise. For example, the housing may be particularly formed or include structure for forming electrical connectors for one or more heaters, thermostats, pump motors or otherwise. Further, the housing may include mounting features for mounting of the pump assembly, such as to a engine component, vehicle component or otherwise.

The housing may be formed of any suitable material. In one exemplary embodiment, the material forming the housing is capable of withstanding elevated temperatures such as temperatures commonly experienced by engine coolant components. More specifically, the housing is capable of withstanding temperatures in a range between about 150° F.-300° F. or greater. Suitable materials include metals, plastics, ceramics, combinations thereof or otherwise. In one particular exemplary embodiment, the housing is formed of metal. Similarly, the housing may be formed using any suitable forming techniques. Examples of suitable forming techniques include casting, molding, stamping, or otherwise. In one particular exemplary embodiment, the housing is formed, at least in part, through a casting process.

The pump assembly further includes a suitable pump 32 for movement of fluid through the second conduit as described herein. In one exemplary embodiment, the pump or components thereof (e.g. actuators or otherwise) are at least partially located within the housing and configured to engage the second conduit. In one configuration, the pump includes an electric motor 56 including a drive shaft 58 engaged with an actuation device 60 of the pump to cause rotational movement of one or more actuators 34 attached thereto. For example, in one configuration of the exemplary embodiment, the pump comprises a peristaltic pump or the like. As previously mentioned, the pump includes a rotational axis that is generally concentric to that of an axis of the second conduit, or otherwise adapted to maintain the pressing squeezing engagement between the actuators 34 and the second conduit 26. In another configuration, except for a motor, substantially all of the pump assembly components are located within the housing. In yet another configuration, all the pump assembly components may be located within the housing. This concentric configuration provides the ability of the rotating actuators to apply a uniform force profile and deflection to the second conduit to cause movement of fluid therethrough.

The motor is connected to the drive shaft to transfer rotational movement thereto and includes suitable connectors 63 for connection to a controller, power source or otherwise. In one exemplary embodiment the motor comprises a rotational motor configured to cause rotation of the drive shaft and hence actuators at a rate between about 10 rpm-200 rpm or greater. However, other rotational speeds are contemplated. It should be appreciated that the rotational speed of the motor, drive shaft and actuators may be based upon the amount of deflection of the second conduit and more specifically the potential fluid flow through the second conduit as a result of a fluid flow restriction moving along the length of the second conduit. In other words, it is contemplated that the greater the deflection of the second conduit by the actuators, the lower the rotational speed may be for a given fluid output. Conversely, a lower amount of deflection to the second conduit by the actuators may require an increased motor speed to obtain given fluid output.

The motor 56 may be configured to rotate clockwise, counterclockwise or both, to move between the second inlet and outlet. Thus the direction of flow of the fluid may be reversed by reversing the direction of the rotation of the pump motor. This may be used to purge a portion of the second conduit when the urea solution is not needed, such as when the vehicle engine is turned off, which may be improved upon through one or more valves (e.g., check valve, solenoid valve or otherwise) located downstream from the pump and openable to the atmosphere to offset negative pressure. In one exemplary embodiment, the motor rotates or causes rotation of the drive shaft, actuation device or actuators in a direction towards the second outlet. Also, rotational speed of the motor or attached components may be generally constant or variable. In one exemplary embodiment, the speed of the motor, actuator device and/or actuators are based upon the required urea solution to be delivered to the exhaust treatment device to maintain efficiency thereof. Examples of suitable motors include metering pumps such as jacketed peristaltic metering pumps. However, the use of other pumps is possible.

The actuator device 60 is fixedly connected to the drive shaft 58 through suitable connection means such as an interface fit, splined or keyed joint between the device and the shaft, or a combination thereof or otherwise. In the exemplary embodiment shown, the actuator device comprises a base member 62, which may be a circular shape, having actuators 34 mounted to an outer mounting portion or boss 64 thereof. The actuator 34 is in the form of a journaled wheel or shaft which in one exemplary embodiment is rotatably mounted. Optionally, actuators 34 may be formed as a part of the base member 62 as a lobe or cam-shaped protrusion. The actuator device may include a number of actuators, which may be based on, in part, a desired flow rate through the second conduit. It is contemplated that the number of actuators on the actuator device may include between about 1-4 or more actuators. It is further contemplated that the actuators may be evenly spaced apart to maintain balance forces on the shaft, base member and actuator device during rotation.

The actuators 34 are mounted to the actuator device through suitable attachment means and include at least a portion that extends beyond the outer periphery of the actuator device. In one exemplary embodiment, the actuators comprise rollers that are rotatably mounted to the actuator device. The rotatable mounting of the actuators may be achieved through pivot connections which may include one or more bearing members 67, or otherwise, for providing rotatable mounting and reduced friction. Further, the actuator device, actuators or otherwise may be formed of or include a friction reducing material.

Optionally, in one exemplary embodiment, the pump assembly includes one or more resistance heaters 42 for heating the urea solution. Such heaters may be particularly advantageous for raising the temperature of the urea solution prior to the temperatures of the first fluid and/or housing reaching optimum temperatures for heating the urea solution. Also, this may be particularly advantageous during cold start of the engine or exhaust treatment system of the pump assembly to melt or otherwise heat urea solution within the second cavity. In one configuration, the housing includes an additional resistance heater 42 located at the second inlet opening, the second outlet opening or both. The one or more additional heaters may be located upstream and/or downstream from the housing. The additional heater includes electrical connections for attaching electrical power to the additional heater.

In one exemplary embodiment, the heater is in power or signal communication with a controller, as described herein, to control an application and/or amount of power (e.g., current) to the additional heaters. Communication between the controller and the heater is achieved through suitable electrical connectors 63 which may be in power or signal communication with a controller, power supply or otherwise.

In one exemplary embodiment, the heater comprises a coiled electrical resistance heater configured to heat the housing located at or approximate to the inlet opening and/or outlet opening. In the configuration shown, the coiled electrical resistance heater is wrapped about the second inlet and outlet openings. In another configuration, the heater comprises a resistance heater configured to heat the urea solution directly, within the urea fluid flow. In yet another configuration, the heater comprises a non-resistance heater such as heated air, an induction heater, microwave radiation, radio waves, ultrasonic energy, infrared energy or other. Other electrical and non-electrical heating configurations are contemplated.

Optionally, the pump assembly further includes one or more temperature sensors 64 for measuring the temperature of the additional heaters, first fluid, urea solution or a combination of them. In the configuration shown, the temperature sensors are located proximate to the second inlet opening, outlet opening or both for determining the temperature of urea solution entering or exiting the pump housing or both. However, it is contemplated that the additional temperature sensors may be located further upstream or downstream from the pump assembly. As with the heaters, in one exemplary embodiment the one or more temperature sensors include a connector 65 for signal communication with another component, such as a controller or otherwise. Accordingly, it is contemplated that the temperature sensed by the temperature sensors may be used to determine whether the additional heaters are used based upon the urea solution temperature, the temperature of the coolant or otherwise.

In one exemplary embodiment, the pump assembly and components associated therewith are in communication with a controller 66, such as power or signal communication. The controller may be configured to communicate with and/or control functions of the pump assembly and components thereof. For example, the controller may be in power or signal communication with the motor for controlling rotational direction and speed of the actuators. The controller may be in power or signal communication with any of the valves described herein for controlling fluid flow through the pump assembly or otherwise. The controller may be in power or signal communication with the temperature sensors or heaters as described herein for controlling additional heating to the urea solution. It should be appreciated that the controller may be configured to communicate with or control other components of, or related to, the pump assembly.

In one exemplary embodiment, the controller receives and stores information transmitted by sensors of the pump assembly, such as temperature sensors, pressure sensors, NO_(X) sensors or otherwise. With this information, the controller continuously calculates the appropriate urea injection rate and timing of the injection. Further the controller adjusts the urea temperature and flow to maintain a precise metered quantity of urea being delivered into an exhaust gas stream, via one or more poppet valves of a dosing module 45 or otherwise. The flow is adjusted by modifying the pump speed that delivers the quantity (e.g., volume) of fluid proportional with the pump speed, hence a positive displacement pump. The pump delivers controlled flow at a relatively high pressure for better fluid atomization (or vapor mixing) in the exhaust gas stream. The control module is also configured to adjust the heater temperature, control the function of a urea supply heater, such as a urea cartridge microwave heater, that melts frozen urea and allows the urea to flow to the pump assembly. The controller also provides an alert signal when a fluid level sensor, such as an ultrasonic level sensing, in the urea supply cartridge detects low levels of urea solution. It should be appreciated that the controller may be configured to control additional aspects of fluid dispensing or dosing or may be configured to control dispensing or dosing in different manners.

The controller may comprise a stand alone controller or form a portion of a more encompassing controller. For example, the controller may be associated with a controller for the emissions control system of the engine. Further, in one particular application, the controller may form a portion of the electronic control module of a vehicle. Other configurations are contemplated.

Exemplary embodiments of the pump assembly of the present invention may be utilized in a variety of applications. For example, the pump assembly may be used with practically any emission producing device including stationary and non-stationary applications. In one particular configuration, exemplary embodiments of the pump assembly may be used with internal combustions engines.

In one more particular configuration, exemplary embodiments of the pump assembly may be used with vehicle engines, and more particularly, diesel engines. It should be appreciated that the teachings described herein can be used in numerous emission reducing applications.

Referring to FIG. 1, an exemplary embodiment of an exhaust treatment system 12 is provided. The exhaust treatment system includes a pump assembly in fluid communication with a coolant system of an engine 38 for causing heating of the pump assembly and fluid flowing therethrough. The pump assembly is in further communication with a urea supply 40 and one or more outlets 44 of a dosing module 45 in fluid communication with an exhaust gas stream. As the coolant travels through the pump assembly, heat generated by the coolant from an engine is absorbed by the pump assembly and the urea solution flowing through the pump assembly. The pump causes the urea to be pumped from the urea supply to the outlet whereby heat from the coolant heats the urea solution. Optionally, the urea solution is further heated by one or more additional heaters 42. The exhaust treatment system is controlled through a controller for metering the flow rate of urea through the pump and optionally coolant through the pump to ensure that a suitable supply of urea is pumped into an exhaust gas stream flowing to an exhaust treatment device 13.

Referring to FIGS. 2-5, exemplary embodiments of pump assemblies 10 are provided. The pump assemblies include a first cavity 16 in fluid communication with a coolant system of an engine. Coolant from the coolant system enters first inlet opening 22 and travels along first conduit 20 to eventually exit through first outlet opening 24. The pump assemblies further includes a second cavity 18 in fluid communication with a urea supply 40. The urea is pumped through the housing and to an outlet in fluid communication with an exhaust gas stream through pump 32. This is achieved through the direct displacement of urea through the second conduit by rotating actuators 34 squeezing and forcing urea solution from the second inlet opening 28 to the second outlet opening 30 and eventually to the outlet 44. During the coolant's travel along the first conduit heat is absorbed by housing 14, which is further absorbed by the urea solution flowing through the housing and second conduit.

Exemplary embodiments of the present invention further contemplate a method of heating a urea solution for delivery to an exhaust treatment system 13. The method includes fluidly coupling a urea pump assembly 10 to a coolant system of an engine 38 to provide an engine coolant flow through the urea pump assembly. The pump assembly is further fluidly coupled to a urea solution supply to provide a urea solution to the urea pump assembly. A motor 56 of the pump assembly 10 is activated through a suitable controller 66. Upon activation, the motor causes rotation of an actuation device 60 having a plurality of rotatably mounted actuators 34. As the actuators engage a conduit receiving the urea solution it squeezes the conduit causing the urea solution to travel through the housing and to an outlet in fluid communication with an exhaust gas stream. During movement of the urea solution through the urea pump assembly, the urea solution is heated by the engine coolant.

While exemplary embodiments have been described and shown, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiments disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims. 

1. A urea pump assembly for an exhaust treatment system, comprising: a housing comprising: a housing chamber, a first fluid inlet and a first fluid outlet, the first fluid inlet being in fluid communication with the first fluid outlet through a first conduit, a second fluid inlet and a second fluid outlet, the second fluid inlet being in fluid communication with the second fluid outlet through a second flexible conduit, the second flexible conduit being located within a portion of the housing chamber and in thermal communication with the first conduit; and a pump located within the housing chamber, the pump being engaged with the second conduit and configured to move fluid between the second fluid inlet and the second fluid outlet.
 2. The urea pump assembly of claim 1, further comprising a first valve for metering fluid through the first fluid inlet and a second valve for metering fluid through the first fluid outlet.
 3. The urea pump assembly of claim 2, wherein the first valve is mounted to the housing through a first connector and the second valve is mounted to the housing through a second connector.
 4. The urea pump assembly of claim 1, further comprising an electric heater located proximate to the second fluid inlet, the second fluid outlet or both.
 5. The urea pump assembly of claim 4, further comprising a temperature sensor in thermal communication with the heater.
 6. The urea pump assembly of claim 1, wherein the pump includes a projecting member rotatable about an axis of the pump, the projecting member configured to compress the flexible member and thereby move a fluid in the flexible member from the second fluid inlet to the second fluid outlet during rotation of the projecting member.
 7. The urea pump assembly of claim 6, wherein the flexible member of the second conduit comprises a flexible tube, wherein the second conduit is arcuate about the axis of the pump.
 8. The urea pump assembly of claim 7, wherein the pump comprises a positive displacement pump and the projecting member is rotatable about the axis at a variable speed and is reversible, the variable speed of the pump controlling a mass flow rate of the fluid flowing through the second conduit.
 9. The urea pump assembly of claim 1, further comprising a third fluid inlet in fluid communication with the second conduit, the third fluid inlet configured to supply air to the second conduit.
 10. An exhaust treatment system, comprising: an exhaust gas conduit extending between an internal combustion engine and an exhaust gas treatment device, the exhaust gas conduit being configured to guide an exhaust gas stream from the internal combustion engine to the exhaust gas treatment device for treatment of the exhaust gas stream; a urea pump assembly for providing urea to the exhaust gas stream, the urea pump assembly comprising: a housing having a first conduit for receiving and guiding a first fluid from the internal combustion engine through a first internal portion of the housing and a second conduit in thermal communication with the first conduit and the first fluid, the second conduit receiving and guiding urea solution through a second internal portion of the housing, a pump located in the second internal portion of the housing, the pump causing movement of the urea solution along the second conduit; and a fluid outlet in fluid communication with the second conduit and the exhaust gas conduit or exhaust gas treatment device, wherein the pump causes dispensing of the urea solution into the exhaust gas stream through the fluid outlet.
 11. The exhaust treatment system of claim 10, wherein the urea pump assembly includes an electrical heater located along a portion of the second conduit for heating the urea solution.
 12. The exhaust treatment system of claim 10, wherein the pump comprises a positive displacement pump that is variable in speed and reversible, the pump being configured to control a mass flow rate of the urea solution through the second conduit.
 13. The exhaust treatment system of claim 12, wherein at least a portion of the second conduit comprises a flexible member and wherein the pump includes a projecting member rotatable about an axis of the pump, the projecting member configured to compress the flexible member to move urea solution along the second conduit and towards the fluid outlet.
 14. The exhaust treatment system of claim 10, further comprising a control module in power or signal communication with a heater, a temperature sensor, a pump motor, a valve or a combination thereof.
 15. A method of heating a urea solution for delivery to an exhaust treatment system, comprising: fluidly coupling a urea pump assembly to a first fluid system of an engine to provide a first fluid flow through the urea pump assembly; fluidly coupling the urea pump assembly to a urea solution supply to provide a urea solution to the urea pump assembly; and activating a motor to cause movement of the urea solution through the urea pump assembly and to cause discharge of the urea solution into an exhaust gas stream, wherein during movement of the urea solution through the urea pump assembly the urea solution is heated by the first fluid.
 16. The method of claim 15, wherein the urea pump assembly includes an electric heater for heating the urea solution.
 17. The method of claim 16, wherein the urea pump assembly includes a temperature sensor for sensing the temperature of the urea solution.
 18. The method of claim 15, wherein the motor includes a positive displacement pump that is variable in speed and reversible, the variable speed of the pump controlling a mass flow rate of urea solution through the urea pump assembly.
 19. The method of claim 18, wherein the positive displacement pump comprises a length of flexible conduit for guiding the urea solution through the urea pump assembly, and wherein the pump includes a projecting member rotatable about an axis of the pump, the projecting member being configured to compress the flexible member along its length to cause movement of the urea solution through the urea pump assembly.
 20. The method of claim 15, further comprising controlling the urea pump assembly using a control module in power or signal communication with a heater, a temperature sensor, a pump motor, a valve or a combination thereof. 